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<div class="title">boost::hana::literals Namespace Reference</div>  </div>
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<p>Namespace containing C++14 user-defined literals provided by Hana.  
<a href="namespaceboost_1_1hana_1_1literals.html#details">More...</a></p>
<table class="memberdecls">
<tr class="heading"><td colspan="2"><h2 class="groupheader"><a name="func-members"></a>
Functions</h2></td></tr>
<tr class="memitem:a85ac3c47d02722a334181aab540e732c"><td class="memTemplParams" colspan="2">template&lt;char ... c&gt; </td></tr>
<tr class="memitem:a85ac3c47d02722a334181aab540e732c"><td class="memTemplItemLeft" align="right" valign="top">constexpr auto&#160;</td><td class="memTemplItemRight" valign="bottom"><a class="el" href="namespaceboost_1_1hana_1_1literals.html#a85ac3c47d02722a334181aab540e732c">operator&quot;&quot;_c</a> ()</td></tr>
<tr class="memdesc:a85ac3c47d02722a334181aab540e732c"><td class="mdescLeft">&#160;</td><td class="mdescRight">Creates a <code><a class="el" href="structboost_1_1hana_1_1integral__constant.html" title="Compile-time value of an integral type.">hana::integral_constant</a></code> from a literal.  <a href="namespaceboost_1_1hana_1_1literals.html#a85ac3c47d02722a334181aab540e732c">More...</a><br /></td></tr>
<tr class="separator:a85ac3c47d02722a334181aab540e732c"><td class="memSeparator" colspan="2">&#160;</td></tr>
<tr class="memitem:a325859c7db2c3f8e6a4bfab5a81a6dcb"><td class="memTemplParams" colspan="2">template&lt;typename CharT , CharT ... s&gt; </td></tr>
<tr class="memitem:a325859c7db2c3f8e6a4bfab5a81a6dcb"><td class="memTemplItemLeft" align="right" valign="top">constexpr auto&#160;</td><td class="memTemplItemRight" valign="bottom"><a class="el" href="namespaceboost_1_1hana_1_1literals.html#a325859c7db2c3f8e6a4bfab5a81a6dcb">operator&quot;&quot;_s</a> ()</td></tr>
<tr class="memdesc:a325859c7db2c3f8e6a4bfab5a81a6dcb"><td class="mdescLeft">&#160;</td><td class="mdescRight">Creates a compile-time string from a string literal.  <a href="namespaceboost_1_1hana_1_1literals.html#a325859c7db2c3f8e6a4bfab5a81a6dcb">More...</a><br /></td></tr>
<tr class="separator:a325859c7db2c3f8e6a4bfab5a81a6dcb"><td class="memSeparator" colspan="2">&#160;</td></tr>
</table>
<a name="details" id="details"></a><h2 class="groupheader">Detailed Description</h2>
<div class="textblock"><p>Namespace containing C++14 user-defined literals provided by Hana. </p>
</div><h2 class="groupheader">Function Documentation</h2>
<a id="a85ac3c47d02722a334181aab540e732c"></a>
<h2 class="memtitle"><span class="permalink"><a href="#a85ac3c47d02722a334181aab540e732c">&#9670;&nbsp;</a></span>operator&quot;&quot;_c()</h2>

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template&lt;char ... c&gt; </div>
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          <td class="memname">constexpr auto boost::hana::literals::operator&quot;&quot;_c </td>
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<p>Creates a <code><a class="el" href="structboost_1_1hana_1_1integral__constant.html" title="Compile-time value of an integral type.">hana::integral_constant</a></code> from a literal. </p>
<p>The literal is parsed at compile-time and the result is returned as a <code>llong&lt;...&gt;</code>.</p>
<dl class="section note"><dt>Note</dt><dd>We use <code>llong&lt;...&gt;</code> instead of <code>ullong&lt;...&gt;</code> because using an unsigned type leads to unexpected behavior when doing stuff like <code>-1_c</code>. If we used an unsigned type, <code>-1_c</code> would be something like <code>ullong&lt;-1&gt;</code> which is actually <code>ullong&lt;something huge&gt;</code>.</dd></dl>
<h2><a class="anchor" id="autotoc_md243"></a>
Example</h2>
<div class="fragment"><div class="line"><span class="keyword">using namespace </span>hana::literals; <span class="comment">// contains the _c suffix</span></div>
<div class="line"> </div>
<div class="line"><a class="code" href="group__group-assertions.html#ga2c5006540936d9f8880e3a39f4fcc035">BOOST_HANA_CONSTANT_CHECK</a>(1234_c == hana::llong_c&lt;1234&gt;);</div>
<div class="line"><a class="code" href="group__group-assertions.html#ga2c5006540936d9f8880e3a39f4fcc035">BOOST_HANA_CONSTANT_CHECK</a>(-1234_c == hana::llong_c&lt;-1234&gt;);</div>
<div class="line"><a class="code" href="group__group-assertions.html#ga2c5006540936d9f8880e3a39f4fcc035">BOOST_HANA_CONSTANT_CHECK</a>(1_c + (3_c * 4_c) == hana::llong_c&lt;1 + (3 * 4)&gt;);</div>
<div class="ttc" id="agroup__group-assertions_html_ga2c5006540936d9f8880e3a39f4fcc035"><div class="ttname"><a href="group__group-assertions.html#ga2c5006540936d9f8880e3a39f4fcc035">BOOST_HANA_CONSTANT_CHECK</a></div><div class="ttdeci">#define BOOST_HANA_CONSTANT_CHECK(...)</div><div class="ttdoc">Equivalent to BOOST_HANA_CONSTANT_ASSERT, but not influenced by the BOOST_HANA_CONFIG_DISABLE_ASSERTI...</div><div class="ttdef"><b>Definition:</b> assert.hpp:239</div></div>
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<a id="a325859c7db2c3f8e6a4bfab5a81a6dcb"></a>
<h2 class="memtitle"><span class="permalink"><a href="#a325859c7db2c3f8e6a4bfab5a81a6dcb">&#9670;&nbsp;</a></span>operator&quot;&quot;_s()</h2>

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          <td class="memname">constexpr auto boost::hana::literals::operator&quot;&quot;_s </td>
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          <td class="paramname"></td><td>)</td>
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<p>Creates a compile-time string from a string literal. </p>
<p>The string literal is parsed at compile-time and the result is returned as a <code><a class="el" href="structboost_1_1hana_1_1string.html" title="Compile-time string.">hana::string</a></code>. This feature is an extension that is disabled by default; see below for details.</p>
<dl class="section note"><dt>Note</dt><dd>Only narrow string literals are supported right now; support for fancier types of string literals like wide or UTF-XX might be added in the future if there is a demand for it. See <a href="https://github.com/boostorg/hana/issues/80">this issue</a> if you need this.</dd></dl>
<dl class="section warning"><dt>Warning</dt><dd>This user-defined literal is an extension which requires a special string literal operator that is not part of the standard yet. That operator is supported by both Clang and GCC, and several proposals were made for it to enter C++17. However, since it is not standard, it is disabled by default and defining the <code>BOOST_HANA_CONFIG_ENABLE_STRING_UDL</code> config macro is required to get this operator. Hence, if you want to stay safe, just use the <code>BOOST_HANA_STRING</code> macro instead. If you want to be fast and furious (I do), define <code>BOOST_HANA_CONFIG_ENABLE_STRING_UDL</code>.</dd></dl>
<h2><a class="anchor" id="autotoc_md366"></a>
Example</h2>
<div class="fragment"><div class="line"><span class="comment">// Copyright Louis Dionne 2013-2017</span></div>
<div class="line"><span class="comment">// Distributed under the Boost Software License, Version 1.0.</span></div>
<div class="line"><span class="comment">// (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)</span></div>
<div class="line"> </div>
<div class="line"><span class="preprocessor">#include &lt;<a class="code" href="assert_8hpp.html">boost/hana/assert.hpp</a>&gt;</span></div>
<div class="line"><span class="preprocessor">#include &lt;<a class="code" href="config_8hpp.html">boost/hana/config.hpp</a>&gt;</span></div>
<div class="line"><span class="preprocessor">#include &lt;<a class="code" href="core_2is__a_8hpp.html">boost/hana/core/is_a.hpp</a>&gt;</span></div>
<div class="line"><span class="preprocessor">#include &lt;<a class="code" href="equal_8hpp.html">boost/hana/equal.hpp</a>&gt;</span></div>
<div class="line"><span class="preprocessor">#include &lt;<a class="code" href="integral__constant_8hpp.html">boost/hana/integral_constant.hpp</a>&gt;</span></div>
<div class="line"><span class="preprocessor">#include &lt;<a class="code" href="length_8hpp.html">boost/hana/length.hpp</a>&gt;</span></div>
<div class="line"><span class="preprocessor">#include &lt;<a class="code" href="string_8hpp.html">boost/hana/string.hpp</a>&gt;</span></div>
<div class="line"><span class="keyword">namespace </span>hana = <a class="code" href="namespaceboost_1_1hana.html">boost::hana</a>;</div>
<div class="line"><span class="keyword">using namespace </span>hana::literals;</div>
<div class="line"> </div>
<div class="line"> </div>
<div class="line"><span class="comment">// By default, this is disabled</span></div>
<div class="line"><span class="preprocessor">#ifdef BOOST_HANA_CONFIG_ENABLE_STRING_UDL</span></div>
<div class="line"> </div>
<div class="line">    constexpr <span class="keyword">auto</span> str = <span class="stringliteral">&quot;Hello world!&quot;</span>_s;</div>
<div class="line">    <a class="code" href="group__group-assertions.html#ga2c5006540936d9f8880e3a39f4fcc035">BOOST_HANA_CONSTANT_CHECK</a>(str == hana::string_c&lt;<span class="charliteral">&#39;H&#39;</span>, <span class="charliteral">&#39;e&#39;</span>, <span class="charliteral">&#39;l&#39;</span>, <span class="charliteral">&#39;l&#39;</span>, <span class="charliteral">&#39;o&#39;</span>, <span class="charliteral">&#39; &#39;</span>,</div>
<div class="line">                                                    <span class="charliteral">&#39;w&#39;</span>, <span class="charliteral">&#39;o&#39;</span>, <span class="charliteral">&#39;r&#39;</span>, <span class="charliteral">&#39;l&#39;</span>, <span class="charliteral">&#39;d&#39;</span>, <span class="charliteral">&#39;!&#39;</span>&gt;);</div>
<div class="line"> </div>
<div class="line">    <a class="code" href="group__group-assertions.html#ga2c5006540936d9f8880e3a39f4fcc035">BOOST_HANA_CONSTANT_CHECK</a>(hana::is_a&lt;hana::string_tag&gt;(str));</div>
<div class="line">    <a class="code" href="group__group-assertions.html#ga2c5006540936d9f8880e3a39f4fcc035">BOOST_HANA_CONSTANT_CHECK</a>(<a class="code" href="group__group-_foldable.html#gaf0f8f717245620dc28cd7d7fa44d7475">hana::length</a>(str) == hana::size_c&lt;12&gt;);</div>
<div class="line"> </div>
<div class="line"><span class="preprocessor">#endif</span></div>
<div class="line"> </div>
<div class="line"><span class="keywordtype">int</span> main() { }</div>
<div class="ttc" id="aassert_8hpp_html"><div class="ttname"><a href="assert_8hpp.html">assert.hpp</a></div><div class="ttdoc">Defines macros to perform different kinds of assertions.</div></div>
<div class="ttc" id="aconfig_8hpp_html"><div class="ttname"><a href="config_8hpp.html">config.hpp</a></div><div class="ttdoc">Defines configuration macros used throughout the library.</div></div>
<div class="ttc" id="acore_2is__a_8hpp_html"><div class="ttname"><a href="core_2is__a_8hpp.html">is_a.hpp</a></div><div class="ttdoc">Defines boost::hana::is_a and boost::hana::is_an.</div></div>
<div class="ttc" id="aequal_8hpp_html"><div class="ttname"><a href="equal_8hpp.html">equal.hpp</a></div><div class="ttdoc">Defines boost::hana::equal.</div></div>
<div class="ttc" id="agroup__group-_foldable_html_gaf0f8f717245620dc28cd7d7fa44d7475"><div class="ttname"><a href="group__group-_foldable.html#gaf0f8f717245620dc28cd7d7fa44d7475">boost::hana::length</a></div><div class="ttdeci">constexpr auto length</div><div class="ttdoc">Return the number of elements in a foldable structure.</div><div class="ttdef"><b>Definition:</b> length.hpp:34</div></div>
<div class="ttc" id="aintegral__constant_8hpp_html"><div class="ttname"><a href="integral__constant_8hpp.html">integral_constant.hpp</a></div><div class="ttdoc">Defines boost::hana::integral_constant.</div></div>
<div class="ttc" id="alength_8hpp_html"><div class="ttname"><a href="length_8hpp.html">length.hpp</a></div><div class="ttdoc">Defines boost::hana::length.</div></div>
<div class="ttc" id="anamespaceboost_1_1hana_html"><div class="ttname"><a href="namespaceboost_1_1hana.html">boost::hana</a></div><div class="ttdoc">Namespace containing everything in the library.</div><div class="ttdef"><b>Definition:</b> accessors.hpp:20</div></div>
<div class="ttc" id="astring_8hpp_html"><div class="ttname"><a href="string_8hpp.html">string.hpp</a></div><div class="ttdoc">Defines boost::hana::string.</div></div>
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